Postdoctoral

Research Interests

Plant Cell and Development

The development of plants and animals and their ability to function requires the programmed death of individual cells. But plants are unique in that whole, differentiated organs, such as leaves and flowers, die as the plant continues to live. This process rids the continually growing plant of appendages that are no longer beneficial. We are investigating the factors that lead to organ death and are asking what initiates this program.

The daylily flower is an excellent model system to study organ senescence. The petals die synchronously and autonomously only 24 hours after the flower opens. We have shown that petal cell death is due in part to reactive oxygen species causing a loss of membrane permeability. Furthermore, the activities of suicide proteins such as proteinases and nucleases increase markedly just after the flower opens. We have also measured increases in the hormone, abscisic acid (ABA), whose addition prematurely causes many of the same changes that would only occur later during senescence.

Using differential display to identify mRNAs that are upregulated during normal senescence or after ABA treatment, 6 cDNAs have been cloned so far, two of which appear to be suicide genes. We are now poised to determine how the genes are regulated, either normally or after ABA additions. We also intend to look for expression of these genes in flowers of tobacco and Arabidopsis, where transformation experiments can be carried out more easily.